Know your blood oxygen concentration and heart rate painlessly and in seconds! Pulse Oximeters have been used in hospitals but they were sold for over $325. Now this high-quality, medical grade, pulse oximeter is affordable and available to anyone concerned about Pulmonary Disease, asthma, and congestive heart failure. The technology is noninvasive ... two red LED lights of different frequencies are transmitted into the tissues of the finger. Features: Low power consumption, automatically power off, and 2 AAA batteries included.